Surface treating machine



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R. O. PETERSON SURFACE TREATING MACHINE b'l IPI' I l lil.

Feb. 23, 1960 Filed April 28, 1958 47 49/-f- II 4% Feb. 23, 1960 R. o. PETERSON 2,925,589

SURFACE TREATING MACHINE Filed April 2S, 1958 2 'Sheets-Sheet 2 IN V EN TOR.

RUBEN O. PETERSON BY MMM AT TORNEYS United States Patento SURFACE TREATIN G MACHINE Ruben O. Peterson, University Heights, Ohio, assignor to The Osborn Manufacturing Company, Cleveland, Ohio, a corporation of Ohio Application April 28, 1958, Serial No. 731,332

37 Claims. (Cl. 515) This invention relates as indicated to a surface treating machine, and more particularly to a machine utilizing power driven rotary brushes for treating and linishing a variety of articles passed therethrough.

A very large number of diverse articles are produced such as small metal stampings, cast metal parts, molded plastic articles and the like which may have ash or burrs thereo-n or superficial coatings of rust and scale, for example, which require to be removed. It is also often desired to round sharp corners and edges and to produce a more pleasing surface finish on the article. A common type of machine employed for such processing is the barrel tumbling machine, a quantity of the articles to be processed being placed in the barrel which is rotated to tumble the articles therein together with various abrasives, pellets and uids, depending upon the particular treatment required. In many cases, blasting or power brushing operations may be preferred, and sometimes such operations are employed to supplement barrel tumbling. The usual power brushing machines, however, have been designed for the processing of relatively large articles of uniform shape such as gears, for example,

and have not been well adapted for the brushing of large quantities of miscellaneous metal and plastic articles.

It is accordingly an important object of my invention to provide a surface treating machine utilizing power driven rotary brushes in a manner to achieve many of the advantages of barrel tumbling.

Another object is to provide such machine through which the work-pieces may be continuously transported as desired.

Still another object is to provide such machine having abrasive or pellet supply means of a superior sort for introducing such treating materials.

A further object is to provide such machine which will be substantially entirely automatic in operation, including recirculation of the treating materials.

Other objects of the invention will appear as the description proceeds.

To the accomplishment of the foregoing and related ends, said invention then comprises the features hereinafter fully described and particularly pointed out in the claims, the following description and the annexed drawing setting forth in detail certain illustrative embodiments of the invention, these being indicative, however, of but a few of the various ways in which the principle of the invention may be employed.

In said annexed drawing:

Fig. 1 is a transverse vertical section through the middle of a machine embodying my invention taken on the line 1 1 on Fig. 2;

Fig. 2 is a longitudinal section through .such machine taken on the line 2 2 on Fig. 1; and

Fig. 3 is a detail view of a reciprocating mechanism suitable for thumping conveyor belts within the machine.

Referring now more particularly to such drawing, the embodiment of my invention there illustrated. comprises a frame or stand having two octagonal end members 1 2,925,689 Patented Feb. 23, .19.60

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and 2 supported on a pair of pivotally mounted legs such as 3 at one end and by a pair of vertical jacks such as 4 at the other end. A plurality of cylindrical rotary brushes 5, 6, 7, 8, 9 and 10 are journalled in supports such as 11, 12, 13, 14, 15 and 16 carried by said end frame members and are driven by corresponding electric motors 17, 18, 19, 20, 21 and 22, brushes 7, 8, 9 and 10 being driven at slower speeds than brushes 5 and 6 through gear reduction means (not shown). The brushes themselves are enclosed within a hexagonal sheet metal housing 23 supported by such end frame members. A vent V connects with such housing through which suction may be applied for the purpose of removing dust and fumes from the operation and maintaining a certain negative pressure at the two ends of the housing wher the work is introduced and removed.

While the upper pair of brushes 5 and 6 are in contact or substantially in contact with each other, and driven in opposite directions so that their respective brush faces are travelling in a downward direction where opposed to one another, the other brushes 7, 8, 9 and 10 will ordinarily be somewhat spaced apart as shown with the gaps therebetween substantially covered by travelling conveyor belts ordinarily having their inner courses driven from right to left as viewed in Fig. 2, that is to say, from the entrance to the exit end of the machine. The lower belt 24 passes about end pulleys 25 and 26 adapted to be driven through power means (not shown) in either direction as may be desired. Similar narrow belts 27 and 28 extend between cylindrical brushes 7 and 9 and between cylindrical brushes 8 and 10 respectively, 4while wider belts 29 and 30 are interposed be tween brushes 5 and 7 and between brushes 6 and 8 respectively. It is accordingly apparent that the central region extending generally longitudinally through the machine is enclosed by such brushes and belts, the brushes being driven so that the bristle ends travel in curved planes transversely of such region, and the belts being driven to travel longitudinally of such region.

The belts may desirably be of rubber-like compositions.

such as compounds containing neoprene (polychloroprene), for example, and be provided with lugs such as 31 adapted better to engage the work-pieces for shifting of the latter.

Work-pieces may be delivered to the entrance end of the machine by means of conveyor belt 32, such work pieces dropping down chute 33 into the central region defined by the cylindrical brushes and conveyor belts for transportation through the machine and eventual deposit upon delivery conveyor 34. The conveyor belts will, of cou-rse, normally be driven at the desired rate of speed to carry the work-pieces through the machine at the proper rate, but their action may be enhanced by tilting the machine longitudinally through the action of jacks 4 and in some cases the belts need not be operated and the work-pieces may be allowed to travel through the machine as a result of such inclination alone. While generally all of the belts may be driven in the same di'- rection and at a desired rate of speed, or intermittently, there are occasions when it may be desired to reverse the direction of travel of the belts at selected intervals so as to cause work-pieces to be shifted back and forth within the region where they are `subjected to the action of the brushes. The work-pieces are thereby subjected to such brushing action for a longer period of time-while being agitated and continuously repositioned to ensure thorough coverage. The longitudinal movement of the conveyor lugs 31 and the `rotation of the brushes in different directions as indicated in Fig. 1 ensure such frequent repositioning of the articles to present all facets thereofv to the action of the brushes. Ordinarily, the two bottom brushes 9and10`will be driven inopposite directions as illustrated so that their opposed surfaces are moving upwardly, with brush 8 being driven in the same Likewise, it may" processed in the same machine, such articles will not -usually lill more than the lower half of the longitudinal central region defined by the arrangement of brushes and belts;

"Thebrushing operation above described may be supplemented and enhanced by application of treating ma- -terials to the work, such treating materials, for example, comprising chips ofstone, pieces of aluminum oxide and .silicon carbide, pieces of wood,'nut hulls and similar things, sand, rouge, pumice, shot pellets, water, detergems, solvents and the like. A hopper 35 for smaller abrasive material particles is mounted above the machine and provided with a bottom delivery slot 36 leading to the nip of two cylindrical brushes 37 and 33. These last'two brushes are power driven (by means not shown) v at adjustablerelatively slow rates in opposite directions so that their opposed engaging faces are both moving downwardly to fmeter, and deliver the granular abrasive considerable distance down downwardly ytapering chute 39 directly above the nip of cylindrical brushes 5 and 6. Consequently, the material is already dropping fairly lrapidly under the influence of brushes 37 and 38 and of gravity, and of an air stream drawn downwardly bybrushes and 6, whenfit is delivered to the high speed brushes 5 and 6, which now project such material down- Y wardly against the work-pieces travelling through the operating region of the machine. By way lof illustration, ,such brushes 37y and 38 may be driven at only a few feet per minute whereas impeller brushes 5 and 6 may be driven at 10,000 surface feet per minute, this being considerably faster than brushes 7, 8, 9 and 10 which will ordinarily be driven at about 100 to 300 r.p.m.

Air pipes 40 and 41 communicate preferably through long narrow nozzles 42 and 43 with the sides of chute 39 in a downwardly angled direction to admit a balanced double curtain of air to assist the downward travel of the particles delivered by the metering brushes 37 and 38. `Such pipes 40 and 41 may be pressurized, but even if merely open to the outer atmosphere, their action is to form two layers of air along the walls of the passageway which is of assistance in facilitating positioning of the stream of abrasive pellets centrally of such passageway and to assist their iow within chute 39. Two pipes 44 and 45 may also be provided 4on either side of chute 39 adjacent the bottom of the latter through which cleaning fluids, for example, may be delivered to the surfaces of the impeller brushes 5 and 6 on each side of the region of entry of the abrasive pellets. By stopping metering brushes 37 and 38 and admittnig the desired uid thro-ugh pipes 44 and 45, the burden within the machine may be sprayed with such fluid alone, thereby to cleanse the burden of loose particles while continuing operation of the machine. After such cleansing operation has proceeded for the necessary period of time, the burden may then be discharged from the machine by action of the conveyor belts in a clean condition free of the abrasive particles, etc.

Optionally, the metering brushes 37 and 38 may be continued in operation for a period after starting the flow of fluid through conduits 44 and 4S, and by this method certain effects may be obtained on the work such as are sometimes referred to in the art as liquid honing or liquid blasting. 40f course, metering brushes 37 and 4 Y 38 may thereafter be stopped and flow of fluid in conduits 44 and 45 continued to cleanse the burden before discharge from the machine.

Hopper 35 is supplied by means of a vertical screw conveyor 46 driven by electric motor 47 through worm gear reduction unit 48 and bevel gear unit 49. The lower end of such screw conveyor extends into a bin 50 adapted to receive the abrasive having descended thereto after having been blasted downwardly by brushes 5 and 6 and after having been worked about the pieces of the burden in the machine by the brushes contacting the work-pieces. I also may provide a continuous screen conveyor 51, the upper course of which is caused to travel from the delivery to the entrance end of the vmachine as indicated in fthe hopper 35, the metering brushes 37 andA 38, and the 3() high speed impeller brushes 5 and 6 spaced substantially material from hopper` 35. Such material next drops a Fig. 2, passing about pulleys 53 and 53. Such screen conveyor is effective to sift out the finer particles which drop through into bin 50, while carrying the larger particles, chips and pieces to bin 54 at the entrance end of the machine but offset laterally of the work transporting conveyor 32. Such larger size abrasive particles, chips and'pieces of treating materials are scooped up from bin 54 by bucket elevator 55 and delivered to hopper 56 from which they are metered by the slowly driven cylindrical rotary brush 57 into chute 58 to enter the operative region of the machine together with the work-pieces descending entrance chute 33.

It will be apparent that the abrasive or pellet delivering system above described and comprising principally therebelow may be utilized in various other types of machines and for projecting such pellets or abrasive f The mecha. nism'described and explained is capable of very precise metering of the treating material along a long narrow against a variety of different work-pieces.

line, and likewise such material may then be impelled at great velocity uniformly against the work along a long' n narrow line.

Pellets thrown by the usual impellers are concentrated at a point of origin and sent outwardly at a very wide angle. The long thin line of abrasive pellets sent out by the mpelling brushes 5 and 6 is uniform with a large portion straight downwardly and at very effective angles. The action of the impeller brushes is considerably enhanced by the fact that the treating material will have accelerated prior to arrival in the nip of the impeller brushes and all of the momentum does not have to be imparted by them. By bringing chute 39 into close proximity of the nip of impeller brushes 5 and 6, and guarding the upper surfaces of Suchbrushes by means of guards 59 and 60, such impeller brushes may also be caused to create considerable downward suction at the bottom exit slot of the chute. In the embodiment of the invention shown and described, the abrading action of the material thus impelled against the work-pieces is much enhanced both by the mechanical tumbling of the latter by the lower brushes,-thereby presenting all surfaces of the work-pieces to the abrasive blast, and by the brushing action of the lower brushes themselves on the work-pieces utilizing the spent abrasive from the blast.

The several conveyor belts will ordinarily move at a rather slow rate of speed and in ways to ensure continual exposure of different areas of all work-pieces and thus to ensure adequate processing of the work-pieces being moved through the machine. In order further to agitate the work-pieces and ensure thorough treatment of all surfaces thereof, I may optionally provide means for thumping the backs of the belts thereby to jog the workpieces within the operating region additionally to ensure continual exposure of different areas to the action of the brushes, abrasive particles and other treating materials.

Such thumping means will more frequently be desired for employment in conjunction with lower agitation and conveyor belt 24, and three such devices 61, 62- and 63 are shown in`Fig'. 2 mounted on support 64 and having upwardly projecting rods such as 65 engaging the underside of an elongated bar B which in turn supports the underside of the upper course of the upper conveyor belt 24. Bar B is itself supported at its ends by means permitting a limited amount of vertical movement of the bar. Referring now more particularly to Fig. 3 of the drawing showing one such device in vertical section, it will be seen that such device may comprise a vibrator of a type well known in the foundry industry for vibrating patterns while drawing the latter from molds. A piston 66 is fitted for vertical reciprocation within cylinder 67, air under pressure being admitted to such cylinder through line 68. Passages are provided through the piston, and outlets are provided from the cylinder bore as indicated effective to cause automatic reciprocation of piston 66 first in one direction and then in the other, the upper end of the piston striking the block 69 forming one cylinder head, with rod 65 constituting a substantially integral extension thereof. A vibration of any desired rapidity may consequently be transmitted to rod 65 and thereby to the upper course of conveyor belt 24 so as to jounce articles within the machine engaged thereby, tending to turn such articles over for subjection to the abrasive action of the blast directed downwardly by impeller brushes 5 and 6 and to brushing action more generally over the whole surface of the articles being processed. In practice, it will frequently be preferred thus to supply air under pressure through line 68 at intervals of only, for example, one-half minute more or less. The jouncing or jolting action thus transmitted not only assists in ensuring that all portions of the work-piece surface are subjected to the abrasive blast and brush action, but also tends to prevent any particular surface portion from being subjected to too prolonged action of brushes or abrasive blast.

For many types of tumbling operations, I prefer to employ both relatively fine abrasive or pellets which may be projected in a blast against the work by means of impeller brushes 5 and 6 and also relatively large chips or the like which are adapted to be fed to the machine by means of metering brush 57 from hopper 56. The two bins 50 and 54 with their respective elevators and the screen conveyor 51 which serves to carry the larger chips to bin 54 While permitting the finer abrasive or shot to drop into bin 50 are effective thus to segregate the two types of treating materials for reuse in the desired manner.

It will be seen from the foregoing that I have provided a novel brushing machine which is also operative to tumble the work both for more uniform brushing of the latter and also better to present the work to an abrasive blast. A true tumbling action is also effected inasmuch as the work-pieces will be turned over and over in conjunction with abrading material. rIhe machine is quite automatic in operation and is adapted to be included in a line of machines designed to perform sequential operations on the work-pieces.

The two lower brushes together with the side brushes 7 and 8 in effect form a trough adapted to receive articles delivered thereto and to tumble and brush such articles. Ordinarily, the machine will be filled with articles to be treated to a level no higher than the tops of brushes 7 and 8, leaving ample room for turning and jogging of the articles as they pass through the machine as well as permitting eective abrading (including peening) action on such articles by treating material projected by impeller brushes 5 and 6. Any desired type of fill may be utilized in the various brushes, including crimped wire bristles, Tampico fiber, and fabric buff material. 'I'Ihe brushes may be formed, for example, of helically wound brush strip of the type disclosed in my prior Patent 27,303,386. Instead of belts 29 and 30, stationary wall Portions may be provided, and in seme cases. only the bottom conveyor and agitator belt 24 will be desired.

6 Furthermore, in some cases the use of any'orall treating material including liquids may be dispensed with and the articles subjected merely to the brushing action of thel -brushes (including brushes 5 and 6, driven at slower speeds) as they pass through the machine.

Other modes of applying the principle of the inven tion may be employed, change being made as regards the details described, provided the features stated in any of the following claims or the equivalent of such be employed.

I therefore particularly point out and distinctly claim as my invention:

l. A machine for surface treating articles comprising a plurality of power driven rotary brushes mounted for rotation about parallel axes arranged generally in a substantially closed circle to define a central operating region ladapted to receive such articles for tumbling Aand brushing action thereon.

2. The machine of claim l', wherein said parallel axes are tilted to facilitate passage of such articles through such operatnig region under influence of gravity.

3. The machine of claim 1, wherein a travelling belt p-asses through such operating region to assist passage of such articles therethrough. v

4. The machine o-f claim l, wherein certain of said brushes are driven in different directions of rotation.

5. The machine of claim l, including means operative to deliver treating material to such operating region.

6. The machine of cla-im l, including `abrasive impelling means operative to impel an abrasive blast against such articles in such operating region.

7. A machine for surface treating articles comprising a plurality of power `driven rotary brushes mounted fory rotation about parallel ares arranged generally in a substantially closed circle to delinea central operating region adapted to receive such articles for tumbling and brushing action thereon, and means for driving a closely opposed pair of said brushes in the upper part of said machine in opposite directions at high speed to impel abrasive downwardly into Such operating region.

8. A machine for surface treating articles comprising a plurality of power `driven rotary brushes mounted for rotation about parallel axes arranged generally in a circle to define a central operating region adapted to receivel such articles for tumbling and brushing action thereon, means for driving a closely opposed pair of said brushes in the upper part of said machine in opposite directions at high speed lto impel abrasive downwardly into such operating region, and means for driving the remaining said brushes at substantially lower speeds.

9. A machine for surface treating articles comprising a plurality of power driven rotary brushes mounted for rotation about parallel axes arranged generally in a circle to define a central operating region adapted to receive such articles for tumbling and brushing action thereon, and means for driving a pair of said brushes in the lower pait of said machine in opposite direct-ions with the opposed portions of their brush faces moving toward such operating region.

l0. A machine for surface treating articles comprising a plurality of power driven rotary brushes mounted for rotation about parallel axes arranged generally in a circle to define a central operating region adapted to receive. such articles for tumbling and brushing action thereon, means for driving a pair of said brushes in the lower part of said machine in opposite directions with the opposed portions of their brush faces moving toward such operating region, and conveyor means interposed between Said'l brush faces extending longitudinally of such operating: region.

l1. A machine for surface treating articles comprising; a plurality of cylindrical power driven rotary brushes mounted for rotation about parallel axes arranged generally to define an article receiving trough, said rotary brushes conjointly forming substantial. portions of both.w the sides and bottom of said trough.

12. The machineof claim 11, wherein two lower rotary brushes define the bottom of such trough and two other rotary brushes define the respective sides of such trough, means for driving said lower brushes in opposite directions with the opposed portions thereof moving upwardly, and means driving said side brushes in the same directions as the adjacent bottom brushes.

13. The machine of claim 11, wherein two lower rotary brushes define ,the bottom of such trough and two other rotary brushes define the respective sides of such trough, means for driving said lower brushes in opposite directions with the opposed portions thereof moving upwardly, means driving said side brushes in the same directions as the adjacent bottom brushes, and a conveyor belt interposed between said two -bottom brushes and extending. longitudinally thereof. e

14. The machine of claim 1l, wherein two lower rotary brushes define the bottom of such trough and two other rotary brushes define the respective sides of such trough, means for driving said lower brushes in opposite directions with the opposed portions thereof moving upwardly, means driving said side brushes in the same directions as ythe adjacent bottom brushes, and conveyor belts interposed between adjacent brushes and extending longitudinally thereof.

15. The machine of claim 11, wherein two lower rotary lbrushes define the bottom of such trough and two other rotary brushes define the respective sides of such trough, means for. driving Isaid lower brushes in opposite directions with the opopsed portions thereof moving upwardly, means driving said side brushes in `the same directions as the adjacent bottom brushes, a conveyor'belt interposed between said two bottom brushes and extending longitudinally thereof, and means operative to jog said belt to agitate such articles.

16. In a machine for surface treating articles having two parallel, generally horizontal cylindrical power driven rotary brushes and a conveyor belt interposed therebetween and extending longitudinally thereof, means operative to jog said belt to agitato articles thereon engaged by said brushes.

17. The machine of claim 16, including means operative to project treating material forcibly against such articles while engaged by said belt and brushes.

18. A machine for surface treating articles comprising a. plurality of cylindrical power driven rotary brushes mounted for rotation about parallel axes arranged generally to define an article receiving trough, two lower brushes defining the bottom of such trough and two other brushes defining the respective sides of such trough, means for driving said lower brushes in opposite directions with the opposed portions thereof moving upwardly, means driving said side brushes in the same directions as the adjacent bottom brushes, conveyor belts interposed between adjacent said brushes and extending longitudinally thereof, means operative to jog the belt intermediate said two lower brushes; means operative to project treating material forcibly against such articles while engaged by said brushes comprising a pair of cylindrical power driven impeller brushes mounted for rotation about axes parallel to and above the aforesaid brushes, means operative to drive said impeller brushes at high speeds in opposite directions with their opposed portions moving downwardly, conveyor belts between said impeller brushes and the respective adjacent side brushes extending longitudinally thereof; a hopper above said impeller brushes, a pair of rotary metering brushes adapted to be driven to deliver treating material from said hopper downwardly toward the nip of said mpeller brushes, a chute extending between said metering brushes and said impellervbr'ushes, -air inlets to both sides of said chute, guard means closely enclosing the uppersides of said impellerjbrushes, liquid dispensing means operative to deliver liquid to said impeller brushes at the respective vsides of Isaid chute; a housing substan entrance and delivery end portions thereof, a suction outlet from said housing whereby the interior of saidhousing may be maintained under negative pressure; a

travelling screen conveyor beneath said lower brushes' operative to transport large pieces of treating material to the entrance end of said machine while permitting small pieces to drop therethrough, an elevator operative to lift such small pieces to said hopper, a` second hopper above the entrance end of said machine, an elevator operative to lift such large pieces of treating material to said second hopper, and metering means operative to feed said large pieces of treating material into such trough together with such articles delivered thereto.

19. The method of surface treating articles which comprises simultaneously tumbling such articles with discrete treating material and subjecting` such articles to brushing action.

20. The method of claim l9, including simultaneously forcibly projecting smaller abrasive particles against such articles.

2l. The method of claim 19, including simultaneously forcibly projecting a liquid against such articles.

22. The method of claim 19, including simultaneously forcibly projecting smaller abrasive particles against such articles, collecting such discrete treating material and smaller abrasive particles, separating them, and separately recirculating them by mixing such discrete treating material with such articles and again forcibly pro- V jecting such smaller abrasiveV particles.

23. The method of claim 19, including jogging such l hopper adapted to contain a supply of discrete particles,`

a pair of opposed rotary metering brushes mounted for rotation about parallel axes beneath said hopper adapted to be driven in opposite directions with their opposed portions moving downwardly to meter particles from said hopper directly downwardly, an enclosed chute beneath said brushes down which such metered particles are adapted to fall, air inlet means to each side of said chute adapted to admi-t air to assist in maintaining such falling particles centrally of said chute, a pair of rotary impeller brushes mounted for rotation about parallel axes with the nip of said impeller brushes located directly beneath said chute to receive such falling particles with the opposed portions of said impeller brushes moving downwardly, and means operative to drive said imeiler brushes at high speed. 28. The treating material projecting means of claim 27, including guard means closely enclosing the upper surfaces of said impeller brushes, and liquid dispensing means operative to deliver liquid to said impeller brushes at the respective sides of said chute.

29. Apparatus for projecting material comprising a pair of opposed rotary metering brushes mounted for rotation about parallel axes adapted to be driven in opposite directions with their opposed portions moving slowly downwardly to meter such material directly downward- `4 ly, a pair of rotary impeller brushes mounted for rotation about parallel axes with the nip of said impeller brushes located to receive such material falling from` said vmetering brushes with the opposed portions of said-v impeller brushes moving downwardly, and means operative to drive said impeller brushes at high speed.

30. The apparatus of claim 29, including means for feeding other treating materials directly to at least one said impeller brush.

3l. The lapparatus of claim 29, including guard means partially enclosing said impeller brushes to assist in developing suction Windage at such nip thereof.

32. The apparatus of claim 29, including means for delivering downwardly inclined air streams against opposite sides of such material falling from said metering brushes to said impeller brushes.

33. The method of projecting material which comprises dropping such material to the nip of pair of opposed impeller brushes, driving such brushes at high speed to impel such material, and delivering downwardly inclined air streams against opposite sides of such material dropping 'to such nip to accelerate the same.

34. A machine for surface treating articles comprising a power driven rotary brush, means operative to drive said brush, means operative forcibly to project hard discrete particles of treating material against such articles while they are subjected to the brushing action of said brush, and means operative automatically to turn such articles while subjected to such treatment to ensure that all surfaces thereof are acted upon.

35. The method of surface treating articles which comprises subjecting them to the brushing action of a cylindrical power driven rotary brush, and simultaneously reciprocating such articles back and forth parallel to the axis of such brush to turn such articles to assist in ensuring that all surfaces of such articles are acted upon.

36. T'he method of operating a brushing machine having a plurality of cylindrical power driven rotary brushes mounted for rotation about parallel axes, and article engaging belts interposed between said brushes and mounted for movement in directions parallel to the brush axes; comprising driving such brushes to tumble and brush such articles, and driving certain of such belts in one direction while driving certain other of such belts in the opposite direction.

37. A machine for surface treating articles comprising a plurality of cylindrical power driven rotary brushes mounted for rotation about parallel axes and arranged for delivery of articles to be treated to one end of the brush assembly and delivery of the treated articles from the other end of said assembly, such articles travelling longitudinally of said brushes which are arranged to engage such articles to brush and tumble them as they pass [through the machine, including means operative forcibly to project hard discrete particles of treating material against such articles while they are thus tumbled.

References Cited in the le of this patent UNITED STATES PATENTS 1,058,460 Porter Apr. 8, 1913 1,927,721 Stevens Sept. 19, 1933 2,742,739 Smith Apr. 24, 1956 

